JPH04177252A - Image formation material - Google Patents

Abstract

PURPOSE:To improve the coloring density of a printed image without any drop in the transmission efficiency of an active beam like ultraviolet by causing a sensitive layer to contain a specified colloidal type dye. CONSTITUTION:A colloidal type dye expressed by the formula I is contained in a sensitive layer. In the formula, R1 and R4 independently stand for a dimethyl amino group, a diethyl amino group, dibutyl amino group or a hydrogen atom, R2 for a methyl group or an ethyl group, and R3 for a methyl amino group, a diethyl amino group, an anilino group, a xylidino group or a hydrogen atom. A suitable amount of dye added to the sensitive layer is 5 to 50% of a total solid content, and further preferably 9 to 20%. According to this construction, an image can be made to color only at the time of heating after printing, without causing dark reaction such as coloring during the irradiation of an active beam. In addition, a printed image of higher density can be obtained, while maintaining image resolution.

Description

[Detailed description of the invention] [Object of the invention]゛ (Industrial application field) The present invention relates to a method for forming nine images.

More specifically, it is a method that utilizes the difference in tackiness between the exposed and unexposed areas of the photosensitive layer and uses an image-forming material made by overlapping a single color or multiple colors. The present invention relates to a high-quality image forming method that allows obtaining similar transfers.

(Prior Art) Conventionally, in the printing industry, it has been common practice to use one-proof printing or prepress proofing as a means of confirming the two-tone finish of the final printed matter before printing. Are known.

Prepress blue has the advantage of being able to predict the finish of the final printed matter without using printing ink, and can be used with overlay or subprint methods depending on the final image quality and various objectives in the plate-making and printing processes. etc. are used accordingly.

In the overlay method, there is a photosensitive layer containing coloring materials according to each color separation mask on a transparent base film.

This film and mask are brought into close contact, exposed to light, developed, and then the respective films are superimposed and calibrated.

Nowadays, new methods that do not use a developing solution or developing gas are being considered, such as in Japanese Patent Application Laid-open No. 63-188088, but this method requires the use of transmitted light, so it is low cost but , the delicate color balance and gradation are impaired from the beginning, and it is not possible to judge the final finish of the printed matter as a reflective object.

Unlike the one-overlay method, the sub-print method provides a hard copy, so its utility value is high and has been published so far, such as in US Pat. No. 3,061)023.

There is also a method, as described in Japanese Patent No. 3060024 and No. 3060025, in which several photopolymer photosensitive layers are laminated on a single support and each color separation image is sequentially formed. In this example, color toner is used as the first coloring substance, and it can be said to be an excellent prepress blue in that it faithfully reproduces the original mask, but as the photosensitive layers are stacked, the diffused reflection in the non-image areas is extremely large. Compared to actual printed matter, the gloss is significantly higher, so the texture is quite different. In addition, the cured layer after exposure to light is brittle and cracks can easily appear on the surface depending on the storage conditions. Moreover, coloring using color toner is not preferable from the viewpoint of work hygiene because the color toner scatters.

Also, 1 Japanese Patent Publication No. 59-97410, 61-1
There is also a prepress proof that can be used for both the overlay method and the subprint method as described in Japanese Patent No. 88537. The advantage of this method is that depending on the purpose of use, if you simply want to check characters, etc., you can check only with the overlay.

If you want to obtain a hard copy for checking delicately colored parts such as patterns, you can simply transfer this to the object to be transferred, which is very versatile. however.

Since it requires a developing process using an organic solvent, it has the disadvantage of creating a poor working environment. Furthermore, regarding the images obtained.

Although it is possible to transfer to a transfer object such as , a photosensitive transparent intermediate layer is interposed between the transfer object and the colored photosensitive layer,
The object to be transferred and the colored photosensitive layer are adhered to each other. Due to the presence of this layer, the double reflected light is diffusely reflected, resulting in a finish that is quite different from the actual printed matter, and the density of the obtained transfer tends to be lower than that of the actual printed matter.

Furthermore, since the thickness of the transferred photosensitive layer is always constant, it is stable as a photosensitive material, but since it is not possible to change the color tone as a prepress blue, the result is a finish that is different from the actual printed material. I end up.

(Problems to be Solved by the Invention) The present inventors formed a photosensitive layer containing a dye and/or pigment on a support, exposed it to one image, and separated the exposed and unexposed areas of the photosensitive layer. , a prepress obtained by transferring an image to an image receptor by cohesive failure of the photosensitive layer between roll nips of an image forming material that causes a difference in adhesion during transfer and transfers the image to an image receptor such as paper. It has been discovered that this method is completely different from conventional prepress blueprints, and reproduces the exact same image and texture as the actual printed material because there is no layer such as an adhesive layer between the printing material and the image forming material. . Specifically, JP-A-6
Materials described in Publication No. 3-147154 and the like can be suitably used.

However, in the above method, the color density of black ink in particular is lower than that of normal printing ink, resulting in a large difference in the quality of the finished image, especially in terms of texture, gloss, etc. Therefore, when using a film made from Hl-UCR plate making, which has strong UCR (under color removal) due to photolithographic techniques, as an original plate, the reproduced color density of each color must be approximately the same as the color density of normal printing ink. If the color density balance, that is, the gray balance is disrupted, it becomes impossible to obtain a prepress blue that is faithful to the original.

Furthermore, since this method performs image exposure using actinic rays, it has been difficult to find a compromise between both light transmission efficiency and printed image quality.

[Structure of the invention]

(Means for Solving the Problems) The present inventors formed a photosensitive layer containing a dye and/or pigment on a support, exposed it to nine images, and transferred the exposed and unexposed areas of the photosensitive layer. To provide an effect of improving the color density of a printed image without impairing the transmission efficiency of actinic rays such as ultraviolet rays in an image forming material formed by transferring an image to an image receptor such as two papers with a difference in adhesiveness. I came to find out.

More specifically, the present invention relates to a material that can stably obtain higher printed image density by adding thermal energy to a bripress proof that uses actinic rays as an image forming means.

Note that, as disclosed in JP-A-2-123360, since there are two or more photosensitive layers, the resulting printed image is reliably stable, but it is difficult to stably supply the material.

Therefore, in order to increase the contrast of a printed image without reducing the actinic light transmittance, it is better to thermally process the printed image after forming the printed image to obtain a higher printing density. , is also preferable from the viewpoint of material manufacturing technology.

More specifically, in the present invention, by adding a material that directly develops color by thermal energy, that is, a thermosensitive color-forming material, to the image forming material, no dark reaction such as color development occurs when irradiated with actinic light. If the color is developed only during heating after printing, it is possible to obtain a printed image with higher density while maintaining the image resolution as before.

Therefore, the transfer material obtained using this material is completely equivalent to a normal printed matter in terms of bristle press proof, which is close to the ideal.

The image forming material that can be used in the present invention essentially consists of a transparent support, a photosensitive layer, and a protective film.

As a support, it is stable against heat, chemical light, etc.

Moreover, it is preferable to use a transparent material that can sufficiently transmit actinic rays. For example, cellulose acetate, polystyrene,
Films or sheets made of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polypropylene, etc. Particularly preferred is a polyethylene terephthalate film or sheet.

Particularly preferred is a polyethylene terephthalate film or sheet from the viewpoints of transparency, thermal stability, two-dimensional stability, and the like.

As a protective film, polyethylene film is rigid and
It is preferable in terms of oxygen permeability, expansion/contraction rate, surface smoothness, adhesion, releasability, etc.

Further, the transparent support or the protective film may be subjected to conductive treatment in order to remove static electricity generated when the protective film is peeled off.

Examples of materials that can be applied to the photosensitive layer of the image forming material of the present invention include:

It consists of (a) a photopolymerizable compound and a coloring agent (which may or may not include a colorant), (b) a photopolymerizable compound, a thermoplastic resin, a colorant, etc., and is used as an additive to initiate photopolymerization. A photopolymerization accelerator, a thermal polymerization inhibitor, a resin plasticizer, a pigment dispersant, a heat-sensitive coloring agent, etc. are used in combination.

As the photopolymerizable compound, at least one selected from monomers, oligomers, and prepolymers is used.

The photopolymerizable compound is not particularly limited, and is preferably one that can be plasticized from a thermoplastic resin at room temperature.

Typical compounds include 2-hydroxyethyl (meth)acrylate and ethylene glycol diacrylate.
Diethylene glycol diacrylate 1.6 hexanediol di(meth)acrylate trimethylolpropane triacrylate pentaerythritol triacrylate, dipentaerythritol hexaacrylate, etc., using one or more of these ethylenically unsaturated compounds as necessary You can.

As the thermoplastic resin (organic polymer binder), a thermoplastic, non-photopolymerizable polymer that has excellent compatibility with photopolymerizable compounds can be used. For example, polyvinyl chloride,
Poly(meth)acrylic acid ester.

Epoxy resin, polyurethane resin, cellulose derivative,
(For example, ethylcellulose, cellulose acetate.

There are synthetic rubbers such as (nitrocellulose) vinyl chloride vinyl acetate copolymer, polyamide resin, polyvinyl acetal resin, diallyl phthalate resin, butadiene-acrylonitrile copolymer, etc. Depending on the required physical properties, these thermoplastic materials can be , or two or more types may be included.

As a photopolymerization initiator, we mainly use one that has low absorption in the visible light region, one that has good compatibility with the photopolymerizable compound, and one that has a photochemically intersystem cross quantum efficiency close to 1.
Preferred examples include benzophenone, benzoin ethyl ether, benzyl dimethyl ketal, azobisisobutyronitrile, 2-chlorothiosanthin, 2-methylthiozanzone, 2-ethylthiozanzone, and 2-isoprobylthiozanzone.

4'-isopropyl-2-hydroxy-2-methylpropiophenone and the like may be used in combination with a photopolymerization accelerator to increase the photopolymerization initiation efficiency. As this photopolymerization accelerator, aromatic-aliphatic tertiary amines and the like are known. For example, Michler's ketone, 4.4
'-bisdiethylaminobenzophenone, etc.

Some accelerators may turn yellow, so
The selection is made taking into consideration promotion efficiency, yellowing, compatibility with the initiator, and the energy and wavelength range of the actinic rays to be used.

Most thermal polymerization inhibitors are aromatic derivatives. What is important in selecting a thermal polymerization inhibitor is the amount added and its compatibility; the amount must be such that it does not interfere with the generation of radicals for photopolymerization, and moreover, it must suppress radicals thermally. Hydroquinone, p-methoxyphenol, t-butylcatechol, pyrogallol and the like are commonly used so far. However, the present invention cannot be controlled even if non-aromatic compounds are combined.

The colorant applied to the photosensitive layer is an organic pigment.

Conventionally used dyes and pigments such as dyes, carbon black, etc. can be used. It is also possible to mix several dyes and pigments to obtain the required hue.

The pigment or dye added to the photosensitive layer is suitably 5 to 50% of the total solid content, more preferably 5 to 50% of the total solid content.

9-20% is preferred.

Thermosensitive color formers include leuco dyes (donors), color developers (
A typical example is a combination of a sensitizer (acceptor), a sensitizer (initiator), etc.

Usually, a fluoran dye is mixed into the leuco dye, a phenolic compound is mixed into the color developer, a sensitizer is used to adjust the sensitivity, and an anti-fading agent is mixed into the storage color stabilizer.

Regarding fluoran compounds, JP-A-59-1997579
No. 9757, 3(N-ethylN-isoanyl)amino-6-methyl-7-anilite fluorane, and the like. Or USP-2548366, USP-36813
No. 90, Japanese Patent Publication No. 51-23204, Japanese Patent Application Publication No. 1983-
Materials such as those described in Japanese Patent Publication No. 162690 and Japanese Patent Publication No. 57-52759 are suitable.

As a color developer, Japanese Patent Publication No. 44-3680,
Publication No. 17741/1974, Special Publication No. 127486/1983
Phenol compounds such as those described in No. 27486 No. 9-10645606456 are suitable.

In addition, since the melting point of the color developer is high, it is used as an auxiliary agent.
p-benzylbiphenyl, ]-hydroxy 2- as described in No. 87094 and JP-A-60-82382;
Melting temperature range, heat of fusion, etc., phenyl naphthoate, fatty acid amides, benzyl p-hydroxybenzoate, etc.
It may be selected based on the efficiency of applied energy. Furthermore, in consideration of storage stability, sulfur-containing phenol compounds, metal complex compounds,
Saccharin, thiodiphenylurea, quinones, etc. can also be used as effective auxiliaries. One or more of these materials may be used in combination.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto. In example.

Parts refer to parts by weight.

Comparative example A photosensitive layer solution having the following composition was prepared.

Diallylisophthalate prepolymer 22.0 parts (Daiso Aji) KAYARAD-DPHA (Mo/7-) 7.0 parts (Nippon Kaji) Benzophenone (Daiichi Kasei) 0.5 parts EAB (Hodogaya Chemical) @) 0.2 parts MA-7 (Mitsubishi Chemical Corporation ■Carbon) 3.0 parts R-52 (manufactured by Hoechst Japan ■)
1.0 part methyl ethyl ketone
40.0 parts toluene 1
0.0 part xylene 1o,
3 Parts Example A photosensitive layer solution having the following composition was prepared.

Diallylisophthalate prepolymer 17.0 parts (manufactured by Daiso Co., Ltd.) KAYARAD-DPHA 7.0 parts Benzophenone (manufactured by Daiichi Kasei Co., Ltd.) 0.5 parts EAB (manufactured by Hodogaya Chemical Co., Ltd.) 0.2 Part MA-7 (manufactured by Mitsubishi Kasei Corporation) 3.0 parts R-52 (manufactured by Hoechst Japan Co., Ltd.) 1.0 parts 3 Diethylamino 6 methyl 7 Anilinofluoran 2.0 parts Hisphenol A 2.0 parts p
-Benzyl biphenyl 1.0 parts Methyl ethyl ketone 40.0 parts Toluene
1000 parts xylene
10.3 parts The colored photosensitive layer formed on the transparent support and the protective film were laminated together using a laminator so as to be in contact with each other to obtain the desired image forming material.

The transparent support side of the image forming materials obtained in Comparative Examples and Examples was brought into close contact with the silver salt side of the original positive mask.

Active light of 50 mj/cm2 was applied using a UV printer, HMW-201KB (manufactured by Oak Seisakusho Co., Ltd.). This image forming material and the original positive mask are peeled off.

Furthermore, the protective film was peeled off, and the image was transferred using a Fast Laminator 8B-700 special model (manufactured by Taisei Laminator Co., Ltd.) to coated paper, pearl coat (manufactured by Mitsubishi Paper Mills Co., Ltd.) and the protective film was peeled off. The forming material is brought into close contact with the material, and a pressure of 4 kg/cm2 is applied. Passing speed 35 cm/m i
When the photosensitive layer was transferred using the nip between the rollers at a roller surface temperature of 70°C, the thickness of the photosensitive layer in the unexposed area was 2.
．． 0μ transfer. This means that the photosensitive layer has a thickness of 80 mm.
% transfer.

Measurement was performed using Macbeth's RD-514. At this time, the dot gain of the 50% halftone dot portion of 15OL/1nch increased by 55%, that is, by 5%.

Table 1 As shown in Table 1, compared to the conventional printing density, the density after transfer was higher in the example in which the heat-sensitive coloring material was added, and
The density after several months remained stable and did not change at all, indicating that there was a sufficient improvement in printing density.

Claims (1)

[Claims] 1. A photosensitive layer containing a dye and/or pigment is formed on a support, and if necessary, a protective film is provided on the photosensitive layer, and imagewise exposed, Due to the difference in tackiness between the exposed and unexposed areas of the photosensitive layer, in an image forming material in which an image is transferred to an image receptor such as paper, the photosensitive layer has the following general formula ▲ mathematical formula, chemical formula, There are tables etc. ▼ (In the formula, R_1 and R_4 are each independently a dimethylamino group, diethylamino group, dibutylamino group or hydrogen atom, R_2 is a methyl group or ethyl group, R_3 is a dimethylamino group, diethylamino group, anilino group, An image-forming material characterized by containing a leuco dye represented by xylidino group or hydrogen atom. 2. The image forming material according to claim 1, which contains a phenol compound as a color developer. 3. The image forming material according to claim 1 or 2, which contains a benzyl compound as a sensitizer.